Split-flow solid fuel ramjet



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ATTORNEY lli JNVENTOR.

R. L. WOLF SPLIT-FLOW SOLID FUEL RAMJET 2 Sheets-Sheet 2 ROBERT L. WOLF TTOHNE Y Nov. 30, 1965 Original Filed Nov. 20v, 1952 United States Patent O 3,220,181 SPLIT-FLOW SOLID FUEL RAMJET Robert L. Wolf, Chesterfield County, Va., assignor to Texaco Experiment Incorporated, Richmond, Va., a

corporation of Virginia Continuation of application Ser. No. 321,608, Nov. 20,

1952. This application Nov. 8, 1962, Ser. N o. 236,782

6 Claims. (Cl. 6035.6)

This application is a continuation of my application Serial No. 321,608, filed November 20, 1952, now abandoned.

My invention relates to improved means for promoting and `supporting combustion in ducted burners and, in particular, to means whereby solid fuels may be better utilized in ramjet engines.

The attractiveness of ducted burners, as used in ramjet engines, resides in their overall simplicity and in the absence of primary moving parts; but, when liquid fuels are employed, fuel-metering becomes involved and complex in terms of the required number of parts and in terms of the responses required of these parts. Various proposals have been made to simplify the fuel-metering problem in this type of power plant by employment of solid fuels. Solid fuels appear attractive because of the possibility of achieving relative mechanical simplicity, and also because certain of such fuels may have substantially greater heats of combustion than the conventional liquid fuels and may, therefore, provide greater overall performance capabilities for a given size or Weight. Solid-fuel briquettes have been proposed as a simple answer to the fuel-metering problem; but because varying air mass flows due to changing flight conditions do not produce proportional changes in the burning rate of the charge, it has been considered impossible to obtain anything approaching a constant equivalence ratio or richness in the air-fuel mixture throughout the life of the briquette charge.

It is, accordingly, an object of the invention to provide improved means for burning solid fuels in burners of the character indicated.

It is another object to provide an improved ramjet construction.

A further object is to provide a system of fuel-metering which is in accord with the structural simplicity of the ramjet engine itself.

It is also an object to provide a means for attaining control over the thrust output of a solid fuel ramjet.

Still another object is to eliminate the need for complex fuel meters in ramjet engines.

It is another object of the invention to provide improved means for operating ramjet engines with fuels having substantially greater heats of combustion than the more conventional fuels.

Other objects and various further features of novelty and invention will be pointed out or will occur to those skilled in the art, from a reading of the following specification in conjunction with the accompanying drawings. In said drawings, which show, for illustrative purposes only, preferred forms of the invention:

FIG. l is a fragmentary view in `side elevation of a ramjet engine incorporating features of the invention, parts being broken away and shown in vertical section to illustrate internal construction;

FIG. 2 is an enlarged fragmentary view of forward parts of a ramjet generally similar to that of FIG. l, but incorporating a modification;

FIG. 3 is an enlarged sectional view taken in the plane 3 3 of FIG. 2;

FIG. 4 is a fragmentary longitudinal sectional view of an alternate ramjet construction incorporating features of the invention;

3,220,181 Patented Nov. 30, 1965 Vice FIGS. 5 and 6 are side-elevation and front-end views, respectively, of a further alternative construction, the forward sectionalized parts of FIG. 5 being taken in the plane SA-SA of FIG. 6, and the rear sectionalized parts being taken in the plane 5B-5B of FIG. 6; and

FIG. 7 is a longitudinal sectional view of the forward part of still another alternative construction embodying my invention.

Briefly stated, my invention contemplates so controlling the rate of surface erosion in a solid-fuel briquette that the dislodged combustible and combusting products of erosion will be discharged into the combustion charnber at a relatively uniform rate, or at a rate more linearly related to the instantaneous air mass-flow; in this manner, thrust may be held substantially constant or may merely be allowed to vary within a given range without entailing any substantial departure from an intended equivalence ratio or richness. Such control may be achieved by selectively constricting a passage for pure air (Le. free of the fuel) into the combustion chamber, or by selectively constricting an air passage through a fuel chamber. In the case of a constricted fuel chamber, the desired control may result as an inherent function of the chamber geometry for a particular ow rate and heat release within the fuel chamber, because choking within the fuel-chamber passage may so cut down the capacity of the fuel chamber to admit further air with increasing total air mass-flows that a greater proportional fraction of such further air mass-flow will in effect be diverted (and thus introduced free of the fuel charge) to create a leaner mixture in the combustion chamber. The converse will apply for decreasing air mass-flows, in which case the choking effect may become relatively less pronounced, so that a greater proportional share of the total available air mass-flow may be accepted at the inlet to the fuel chamber.

As indicated, choking may proceed merely as an inherent function of the burning charge itself, but as more of the charge is eroded, the total cross-section available for gas flow through the fuel chamber will increase. In the forms to be described, I prefer to offset this tendency to produce a continuously increasing cross-section by providing auxiliary constriction means of a material that will not erode at anything like the rate of erosion of the fuel charge, so that the same or virtually the `same constricted opening (rather than the instantaneous effective cross-section of a passage determined only by the eroding charge) will determine the limit for the chocking condition. In one form, the constriction may be merely a fixed rugged orifice at the exhaust outlet of the fuel chamber, and, in another form, the nature of the inlet to the fuel chamber may provide a control for the fractional quantity of air admitted and, therefore, of the erosion rate of the fuel charge.

As indicated generally above, it is basic to the invention that additional air, free (or relatively free) of fuel, shall be admitted to the combustion chamber to thin or lean out the mixture for burning at the desired richness. Thus, the method of the invention contemplates generating an excessively rich mixture within the fuel chamber, and independently adding relatively pure air for combustion at the desired richness.

To admit such thinning air, a variety of alternative structural combinations may be devised. In one form, the burner may present the appearance of a conventional ramjet with an elongated tubular body having a primary air inlet at the nose, and with a combustion chamber and exhaust outlet at the other end. The fuel chamber may comprise a tank wholly contained within the engine body and having a through passage characterized by an air inlet at the upstream end and an exhaust outlet at the downstream end, the fuel chamber being spaced from the inner wall of the engine body so as to provide or define an additional duct of annular or generally annular shape. In this first form, therefore, the total air flow (serving both the fuel chamber and the auxiliary air supply) is taken in at one point, and the air flow is divided internally of the engine. In other forms, air for the fuel chamber and the pure, or leaning out, air are taken independently from the slip stream. In one case, the air inlet for the fuel chamber is at the nose, while scoop means on the side of the body bring in free air near the downstream end of the fuel chamber; in another form,

the nose is solid, and the air for the fuel chamber is introduced at the base of the nose through further scoop means; nally, in a third form, both the air for the fuel chamber, and the air for the auxiliary air supply are brought in independently from forward nose locations.

Referring to FIG. 1 of the drawings, my invention is shown in application to a ramjet engine which may be of a type particularly suited to propulsion and flight at supersonic speeds. The engine may comprise an elongated tubular body tapering at a nose section 11 to dene an inlet opening 12 on the axis of the configura- Air admitted at the inlet 12 may be compressed in a diffuser 13 comprising a tapered inner wall dening with the external part 11 of the nose an annular space 14 for accommodation of guidance equipment or high explosive, as suggested by the shading. Air admitted through inlet 12 and compressed by diffuser 13 may pass to a combustion chamber 15, communicating directly with an exhaust outlet 16, which may or may not include a nozzle, depending upon the desired performance of the engine. Tail-iin members 17 may provide aerodynamic stability, and for control purposes additional wings, fins, or ippers may be mounted amidships in accordance with techniques which are known and which are, therefore, not shown or further discussed herein.

In accordance with a feature of the invention, I provide a fuel chamber for controlled erosion and supply of combusting and combustible fuel; such chamber may ,be wholly contained within the body 10 and may operate from a controlled fraction of the total air mass-flow, as admitted at the inlet 12. The fuel chamber may be so constituted and oriented Within the body 10 as to permit a substantial supply of free air, or air substantially free of the combusting and combustible fuel products, for admission to the combustion chamber 15 independently of the fuel-rich products developed within the fuel chamber. For the coaxial configuration shown in the drawings, the two ducts or passages necessary for this purpose may be defined by mounting an elongated tubular member 18 within the body 10, so that one duct may be defined in the annular space between tubular member 18 and the inner wall of the burner, fand so that the other duct may be defined within the tubular member 18 itself. Either one of these ducts may be treated as the fuel chamber; thus, for example, solid fuel may line either or both of the surfaces defining the annular air space between tubular member 18 and the inner wall of the burner. However, in the form shown, I treat the interior of the tubular member 18 as the fuel chamber.

The fuel chamber 18 may be mounted on radial struts 19 within the burner and may be characterized by a through passage having an air inlet 20 and an exhaust outlet 21. The solid fuel charge may be of annularbriquette construction and so formed as to t snugly within the inner surface or wall of the chamber 18 and to define a continuous inner opening or passage. solid fuel may be of single-briquette construction, extending in one piece for the full effective length of the fuel charge, but I have shown my preference for a stacked plurality of adjacent smaller annular briquettes 22, for greater convenience in assembling the total charge.

In order to insure the smooth initiation of burning, I

The

provide ignition means in the form of one or more squibignited V(or otherwise ignited) high-heat pyrotechnic ares, as at 23. The flare composition 23 may be contained in a are cartridge and bodily inserted in place within suitable recesses (24) in one or more of the supporting struts 19, but I have shown the composition to have been packed directly into such recesses (24). The squib or other igniter for the flare 23 may be contained in or packed with the are composition 23, in the region in which it is desired to initiate burning; but since such techniques are well known, I have not illustrated the ignition squib. Suice it to say that, for the form shown, the flare composition 23 may be first ignited at the forward end of recess 24, so that the hot products of flare combustion may be passed through an opening 25 in the chamber 18 at the forward end thereof, and battle means 26, which may be merely a lug struck out of the body of chamber 18 (as in the process of forming the opening 25), may serve to direct the flare flame directly upon the nearest element 28 of the solid-fuel charge. The composition of the forward briquette 28 may be the same as that characterizing the other briquettes 22, but I prefer to employ a more readily burnable mixture in the briquette 28, so that the briquette 28 may constitute a steady hot source for the continued promotion of burning and erosion of the remaining briquettes 22, at least during the early phase of operation Iof the burner.

In operation, the total air mass-ow admitted through means 12 will be divided by the very nature and location of the fuel chamber 18, so that pure air may continuously pass in the annulus between chamber 18 and the burner body 10, for discharge directly into the combustion chamber 15. The other fraction of the total air massflow will be received in the fuel chamber, and, once the flare 23 has ignited the leading briquette 28, the flow of air and hot products in the fuel chamber 18 will erode ,briquettes 22 more or less uniformly and in a radially As the charges 22 erode progressively outwardly, the eifective cross-section of the passage within the fuel chamber 18 changes, and a tendency develops toward excessive discharge of erosion products for a given massiiow in the final stages of propulsion. While this tendency may be desirable in certain applications, I illustrate means to offset the tendency and to promote a more uniform discharge of erosion products; for such purpose,

vauxiliary throttling means -may characterize either the pure-air of the fuel-rich passages, and, in the form shown in FIG. 1, a throttling characteristic is achieved at the exhaust outlet end 21 of the fuel chamber. The desired regulation may be effected by one or more constriction or orifice plates at 21, such plates being of a material having a substantially lesser rate of erosion than the briquettes 22. The effective cross-section of the orifice opening may depend upon the desired performance of the engine; thus, it should be of a size to provide the intended steady-state equivalence ratio or richness in the oombustion chamber 15. If such steady-state equivalence ratio is desired for substantially the full life of the engine, kthen the opening at 21 may be substantially equal to or less than the initial (i.e., un-eroded) effective cross-sectional area of the passage within the solid charges 22, 28; in the form shown, the oriceconstriction area is slightly less than the fuel-charge opening tarea. If, on the other hand, it is desired to produce a relatively low initial ing 21, then the initial size of the opening 21 may be greater than that of the initial briquette opening, as will be understood.

With the throttling means 21, it Will be seen that I provide a definite (i.e., choking) limit to the fiow which can take place within the fuel chamber 18; this limit is so insubstantially related to the extent to which the fuel charge has been eroded or consumed, that a substantially constant regulation may be achieved for a substantially constant inlet mass-flow. This will mean the constant, or substantially constant, fractional admission of air at 20, and that consumption or erosion of the fuel charge will be proportioned accordingly.

Although I have described the nature of the orifice 21 in such a way as to provide regulation for a substantially constant equivalence ratio or richness throughout a given fiight, it will be understood that by careful selection of materials for the orifice means 21, a predetermined desired erosion may take place in the orifice means 21 as a function of time in fiight. Thus, the orifice means 21 may constitute a means for controlling increases in the equivalence ratio or richness during flight, as may be necessary to fit certain particular application requirements.

In practice, I have found satisfactory results to be obtainable with the configuration shown in FIG. 1. In such experience, the charge for briquettes 22, 28 has been composed of powdered magnesium as the fuel, in conjunction with sodium nitrate as an oxidizer, and with linseed oil as a binding agent. For the briquettes 22 constituting the principal fuel cha-rge, the proportions employed may be in the order of 93 parts magnesium, 5 parts sodium nitrate, and 2 parts linseed oil. As indicated, this principal part of the charge may be cast as a single unit; but if small briquette units such :as the units 22 are employed, then I prefer that the charge interfaces be sealed, as with rubber cement, upon assembly in the fuel chamber 18. The upstream charge 28 may be integrally formed with the lead briquette 22 of the main fuel charge, but in the form shown, this upstream charge 28 is a separate briquette; its composition differs from that of the others, in that a greater proportion of oxidizer is employed, as in a mixture of 83 parts magnesium, 15 parts sodium nitrate, and 2 parts linseed oil.

As indicated above, other means may be employed for admission and treatment of the respective air supplies and for establishing a controlled regulation of the airflow division. In FIG. 2, structural features may in every respect resemble those described for the engine of FIG. 1, except that the inlet opening for the fuel chamber 1S incorpo-rates a variable constriction for fiow-control purposes. Variation of the effective inlet opening for the fuel chamber 18 may be `achieved by relatively rotating conical shutters, as by employing a plurality of angularly spaced fixed shutter blades 30, and a corresponding plurality of similarly spaced rotatable shutters 31. The shutters 31 may be formed on a conical member 32, surrounding the diffuser 33 iat the inlet to the fuel chamber 18, and I have shown the m-ounting of revoluble shutter 31 upon antifriction-bearing means 34, carried by fixed parts of the fuel chamber 18. It will be understood that for one relative angular position of the shutters 30, 31, all openings between shutter elements may be radially aligned and, therefore, a maximum opening may be provided for admission of air to the fuel chamber 18. For other relative angular positions, the effective inlet opening for chamber 18 is reduced, and a minimum opening is achieved when one set of shutters 3f) completely blocks the spaces between the other set of shutters 31.

Various means may be employed for setting the effective shutter opening at 30, 31, and for thus determining the fractional supply of air admitted within the fuel chamber 18; also various prime-mover devices, such as radiocontrolled motors, pressure-responsive servos, and the like, may actuate the shutter to determine such opening. In the form shown, I have merely schematically desig- 6 nated such actuating means, prime movers or servos by a crank or rocker a-rm 35. Actuating means 35 may be contained within a contr-ol compartment in the annular space between the diffuser 13 and the nose shell 11; the drawing suggests that this control compartment may utilize a relatively small part of the spiace 14 normally primarily available for other instrumentation or for an eX- plosive charge. The crank 35 may actuate control wires 36, 37, passing through separate guide tubes or Bowden cables 38, 39 contained within the leading edge of one of the struts 19, for connection (as at 46', 41) to the movable shutter elements 31, 32. It will be understood that, assuming an intermediate shutter position as depicted in FIG. 3, a clockwise actuation of rocker 35 (in the sense of FIG. 2) will pull cont-rol wire 36 and relax control wire 37, s-o Vas further to close the effective opening for admission of air to the fuel chamber 13; counter-clock- Wise rotation of rocker 35 will accomplished the opposite result of opening the inlet to the fuel-chamber diffuser 33.

The described construction of FIGS. 2 and 3 cmay be used with or without sa downstream fixed orifice, as at 21 in FIG. 1, depending upon the performance lrequirements. If used Without the orifice 21, then the means 35 may perform the function of throttling down the air admitted to the fuel chamber 18 as the fuel briquettes 22 become more consumed and, therefore, as the effective opening within such briquettes 22 becomes enlarged during the progress of a flight. Alternatively, the control means 35 may be viewed as a means for providing programmed increases and decreases in equivalence ratio or richness during the same fiight, regardless of the extent to which the fuel may have been consumed.

In FIG. 4, I show an alternative ramjet configuration in which the air supply for the fuel chamber, andthe air supply for air substantially free of the eroded fuel, are separately and independently taken from the external air stream. Thus, a relatively restricted inlet opening 50 at the very nose of the ramjet may probe for air to be supplied within the fuel chamber 51. Such air may be diffused in a diffuser section 52, defining with the outer nose shell 53 a warhead or instrumentation space 54. Briquettes 55 may be provided, as previously described, in adjacent stacked relation to define the principal fuel charge; and a plurality of iiares 56 may be secured to the inner wall of the diffuser 52, or of the main body 57, as shown, and directed with the discharge ends thereof facing downstream at an upstream briquette 58 containing a relatively rich supply of oxidizer. As previously described, the downstream end, or exhaust outlet, for the fuel chamber may be characterized by a constriction or orifice 59, so as to provide a limit, or a controlling infiuence, on the flow that might be accommodated by the fuel chamber 51.

Auxiliary inlet air may be derived from a shroud circumferentially continuously surrounding the body 57 of the ramjet and providing a continuous annular opening for discharge into the combustion chamber 60. However, in the form shown, I provide a plurality of separate scoops or inlet diffusers 61, 62 at angularly spaced positions about the body 57 and preferably equally angularly spaced about the body 57. The effective frontal area or total inlet area for the scoop means 61, 62 should, of course, be so proportioned to the openings 50, 59 as to produce the desired equivalence ratio or richness in the combustion chamber 60, and I prefer that the full frontal scoop areas be spaced outwardly from the body 57, so as to avoid such restriction of intake iiow at 61, 62 as might otherwise be occasioned by boundary-layer conditions alongside the body 57. In flight, choking within the fuel chamber 51 will tend to maintain a substantially constant fiow of locally vover-rich mixture and, therefore, of combustible products into the combustion chamber 60 for any given constant fiight condition, and over the full length of a fiight. Increases in flight speed, which would ordinarily be accompanied by substantial increases in inlet air mass-flow at 50 and at 61, 62, may in some cases be accompanied by greater proportional increases at 61, 62 than at 50, with the result that the equivalence ratio or richness may tend to stay constant.

In FIGS. and 6, I show a further modification of the invention wherein the total available inlet area is still divided externally of the ramjet, but wherein the inlet air for the fuel chamber 65 is admitted through side-inlet scoops or diffusers 66, 67 formed at the base of the nose section 68. Other parts of the construction of FIGS. 5 and 6 mayresemble those of FIG. 4 and have, therefore, been given corresponding reference numerals. As will be seen from the front View of FIG. 6, I prefer that side-inlet diffusers or scoops 66, 67 shall be angularly spaced from the side-inlet diffusers 61, 62, so that minimum blanking effects will be produced by the forward diffusers upon the rearward diffusers. It will be appreciated that the construction of FIGS. 5 and 6 lends itself to a more efficient utilization of the total volume within the nose 68, and this space may again be devoted to instrumentation or to an explosive warhead, as suggested by the shading 69.

In FIG. 7, I show a still further alternative construction, in which air is again independently sampled directly from the slipstream for separate diffusion, at 70 for the fuel chamebr 71, and at 72 for the pure-air supply to the combustion chamber 73. The fuel chamber 71 may generally resemble that described in connection with FIGS. l and 2, except that ignition flares 74 for initiating combustion of the charge are shown fully contained within the forward end of the fuel chamber 71. The inlet diffusers 70, 72 may be so formed as to define annular spaces 75, 77 between their respective outer nose shells, as for the accommodation of control equipment in one space and warhead equipment in the other space. The diffuser 72 may be defined by the developing cross-sectional area between the inner wall of the outer or main ramjet body 78 and the outer wall of the fuel chamber 71; in the form shown, the diffuser 72 extends substantially lall the way to the downstream end of the fuel chamber 71. I have shown small, thin radial struts 79, 80 supporting the chamber 71 at axially spaced locations.

It will be seen that I have provided ingenious means for automatic self-metering of fuel in solid-fuel ducted burner configurations. The self-metering characteristic of the various constructions that have been described lends itself particularly to ramjet engines for use at supersonic flight speeds. Not only does my construction afford relatively precise control over the equivalence ratio or richness throughout flight, but it makes possible the utilization of fuels having greater heats of combustion per unit volume and/or per unit Weight than is the case for liquid fuels customarily employed. For most applications, it will be found possible to achieve the desired automatic accurate metering of the fuel regardless of the extent of fuel consumption, totally without dependence upon moving parts, thus avoiding use of the pumps, the pressure-responsive devices, and the associated plumbing that are characteristic of liquid-fuel metering. Quite aside from the above-described uses of the invention in ramjet applications, I have found that burners of the type shown and described may, under certain circumstances, produce substantial volumes of smoke and may, therefore, serve as smoke generators; in this connection, the burner of FIG. 4 has been found to produce a particularly good smoky wake, and this may be desirable for purposes of camouflage to be laid down by high speed aircraft.

While I have described my invention in detail for the preferred forms shown, it will be understood that modifications may be made within the scope of the invention as defined in the claims which follow.

I claim:

1. A solid-fuel ram air burner comprising a combustion chamber having an exhaust outlet therefrom, a fuel chambensaid fuel chamber having a first opening communicating with a source of ram air and a second opening communicating with the combustion chamber, a solid-fuel charge positioned about the inner wall of the fuel chamber between the first and second openings in the fuel chamber, a passage through the solid-fuel charge cornmunicating with the first and second openings and varying in cross-sectional area with the progressive erosion of the solid-fuel charge during 4combustion erosion thereof, a generally non-erodible orifice forming member associated with one of the first and second openings for restricting the potential rate of fiow of combustion products and uncombusted fuel from the solid-fuel charge into the combustion chamber upon combustion erosion of the solidfuel charge to provide a predetermined fuel-rich mixture for the combustion chamber at least during the latter stages of combustion erosion of the solid fuel, and further means for directing ram air directly into the combustion chamber bypassing the ram air flow through the solid-fuel charge in the fuel chamber.

2. A solid-fuel ram air burner comprising a cornbustion chamber having an exhaust outlet therefrom, a fuel chamber, said fuel chamber having a first opening communicating with a source of ram air and a second opening communicating with the combustion chamber, a solid-fuel charge positioned about the inner wall of the fuel chamber between the first and second openings in the fuel chamber, a passage through the solid-fuel charge communicating with the first and second openings and varying in crosssectional area with the progressive erosion of the solidfuel charge during combustion erosion thereof, a generally non-erodible orifice forming member mounted in said second opening for restricting the potential rate of flow of com'bustion products and uncombusted fuel into the combustion chamber upon combustion erosion of the solid-fuel charge to provide a predetermined fuel-rich mixture for the combustion chamber `at least during the latter stages of combustion erosion of the solid fuel, and further means for directing ram air directly into the combustion chamber 'bypassing the ram air flow through the solid-fuel charge in the fuel chamber.

3. A solid-fuel ram air burner comprising a combustion chamber having an exhaust outlet therefrom, a fuel chamber, said fuel chamber having a first opening communicating with a source of ram air Iand a second opening communicating with the combustion chamber, a solid fuel charge positioned about the inner wall of the fuel chamber between the first and second openings in the fuel chamber, a passage through the solid-fuel charge communicating with the first and second openings and varying in cross-sectional area with the progressive erosion of the fuel charge during combustion erosion thereof, a generally non-erodible orifice forming member mounted in said second opening for restricting the potential rate of fow of combustion products and uncom'busted fuel into the combustion chamber upon combustion erosion of the solid-fuel charge to provide a predetermined fuel rich mixture for the combustion chamber, said generally nonerodible orifice forming member having an orifice area less than the area of the passage through the solid-fuel charge prior to combustion erosion of the solid-fuel charge, and further means for directing ram air directly into the combustion chamber bypassing the ram air fiow through the solid-fuel charge in the fuel chamber.

4. A solid-fuel ram air burner comprising a combustion chamber having an exhaust outlet therefrom, a fuel chamber, said fuel chamber having a first opening communicating with a source of ram air and a second opening communicating with the combustion chamber, a solid-fuel charge positioned about the inner wall of the fuel chamber between the first and second openings in the fuel chamber, a passage through the solid-fuel charge communicating with the first and second openings and varying in cross-sectional area with the progressive erosion of the fuel charge during combustion erosion thereof, an orifice forming member provided at the first opening communicating with the source of ram air for restricting the potential rate of flow of air into the fuel chamber and the potential rate of flow of combustion products and uncombusted fuel into the combustion chamber upon combustion erosion of the solid-'fuel charge to provide a predetermined fuel-rich mixture for the combustion chamber, means for varying the effective area of the orifice in the orifice-forming member, and further means for directing ram air directly into the combustion chamber bypassing the ram air flow through the solid-fuel charge in the fuel chamber.

S. A solid-fuel ram air burner comprising a housing, said housing having a ram air inlet at the forward end thereof and an exhaust outlet at the rearward end, a combustion chamber communicating at its rearward end with the exhaust outlet, a fuel chamber, said fuel chamber having Ia first opening communicating with the ram air inlet and a second opening communicating wit-h the combustion chamber, a solid-fuel charge positioned about the inner wall of the fuel chamber between the first and second openings in the fuel chamber, a passage through the solid-fuel charge communicating with the first and second openings and varying in cross-sectional area with the progressive erosion of the solid-fuel charge during combustion erosion thereof, a generally non-erodible orifice forming member between the first opening in said fuel cham'ber and the ram air inlet for restricting the potential rate of flow of ram air into the fuel chamber and the potential rate of flow of combustion products and uncombusted fuel from the `solid-fuel charge into the combustion chamber upon combustion erosion of the solid-fuel charge to provide a predetermined fuel-rich mixture for the combustion chamber, means for varying the area of said generally non-erodible orifice-forming member, duct means connecting the combustion chamber with the ram air between the ram air inlet and the generally non-erodible orifice-forming member for directing ram air directly into the combustion chamber bypassing the ram air flow through the solid-fuel charge in the fuel chamber.

6. A solid-fuel -ram air burner comprising a housing, said housing having a ram air inlet at the forward end thereof and an exhaust outlet at the rearward end, a combustion chamber communicating at its rearward end with the exhaust outlet, a fuel chamber, said fuel chamber having a first opening communicating with the ram air inlet and a second opening communicating with the combustion chamber, a solid-fuel charge positioned about the inner wall of the fuel chamber between the first and second openings in the fuel chamber, a passage through the .solid-fuel charge communicating with the first and second openings and varying in cross-sectional areas with the progressive erosion of the solid-fuel charge during combustion erosion thereof, a generally non-erodible orilice forming member mounted in the second opening in said fuel chamber for restricting the potential rate of flow of combustion products and uncombusted fuel from the solid-fuel charge into the combustion chamber upon combustion erosion of the solid-fuel charge to provide a predetermined fuel rich mixture for the combustion chamber, -duct means connecting the combustion chamber with the ram air lbetween the ram air inlet and the first opening in said fuel chamber for directing ram air directly into the combustion chamber bypassing the ram air flow through the solid-fuel charge in the fuel chamber.

References Cited by the Examiner UNITED STATES PATENTSr 2,683,415 7/1954 Wilson 60-35.6 X

FOREIGN PATENTS 798,489 3/ 1936 France. 879,123 11/ 1942 France. 669,014 3/1952 Great Britain. 243,957 2/ 1947l Switzerland.

MARK NEWMAN, Primary Examiner.

ABRAM BLUM, Examiner. 

1. A SOLID-FUEL RAM AIR BURNER COMPRISING A COMBUSTION CHAMBER HAVING AN EXHAUST OUTLET THEREFROM, A FUEL CHAMBER, SAID FUEL CHAMBER HAVING A FIRST OPENING COMMUNICATING WITH A SOURCE OF RAM AIR AND A SECOND OPENING COMMUNICATING WITH THE COMBUSTION CHAMBER, A SOLID-FUEL CHARGE POSTIONED ABOUT THE INNER WALL OF THE FUEL CHAMBER BETWEEN THE FIRST AND SECOND OPENINGS IN THE FUEL CHAMBER, A PASSAGE THROUGH THE SOLID-FUEL CHARGE COMMUNICATING WITH THE FIRST AND SECOND OPENINGS AND VARYING IN CROSS-SECTIONAL AREA WITH THE PROGRESSIVE EROSION OF THE SOLID-FUEL CHARGE DURING COMBUSTION EROSION THEREOF, A GENERALLY NON-ERODIBLE ORIFICE FORMING MEMBER ASSOCIATED WITH ONE OF THE FIRST AND SECOND OPENINGS FOR RESTRICTING THE POTENTIAL RATE OF FLOW OF COMBUSTION PRODUCTS AND UNCOMBUSTED FUEL FROM THE SOLID-FUEL CHARGE INTO THE COMBUSTION CHAMBER UPON COMBUSTION EROSION OF THE SOLIDFUEL CHARGE TO PROVIDE A PREDETERMINED FUEL-RICH MIXTURE FOR THE COMBUSTION CHAMBER AT LEAST DURING THE LATTER STAGES OF COMBUSTION EROSION OF THE SOLID FUEL, AND FURTHER MEANS FOR DIRECTING RAM AIR DIRECTLY INTO THE COMBUSTION CHAMBER BYPASSING RAM AIR DIRECTLY INTO THE COMBUSTION CHARGE IN THE FUEL CHAMBER. 